Steven S. Nicholson | 4/21/2005 11:03:54 PM
Canadian officials recently confirmed a case of Bovine Spongiform Encephalopathy, also known as "mad cow disease," in an Alberta dairy cow little more than a year after a cow in the state of Washington was diagnosed with the disease – the only U.S. case so far.
Bovine Spongiform Encephalopathy, frequently called BSE for short, is relatively unknown to the public, experts say.
In the year since the Washington state case in Dec. 2003, U.S. officials have kept a close eye on the domestic herd, according to LSU AgCenter veterinarian Dr. Steve Nicholson.
Since the 2003 incident, U.S. meat packers have discontinued the slaughter of cattle with evidence of impaired nervous system activity – often called "downer cows" – Nicholson said.
The number of cattle tested at slaughter during 2004 increased markedly, and all tests were negative, Nicholson added.
In addition, importation of cattle from Canada, where the infected Washington cow originated, was banned throughout 2004. And the Canadian animal health agency increased testing of cattle for BSE.
The recent finding of a BSE-positive cow in Canada and a quarantine of the herd has not yet caused the U.S. Department of Agriculture to cancel plans to begin allowing some Canadian cattle into the United States later this spring, Nicholson said.
To clear up some misconceptions or questions arising from BSE, Nicholson provided answers to some of the questions being raised.
Could BSE spread across the country and infect my cattle? No, BSE is not a contagious disease. It is not transmitted by animal-to-animal contact.
How do cows contract the disease? By eating feed containing tissues from a cow that had the disease. To prevent this problem, the practice of feeding rendered ruminant byproducts to cattle and other ruminants was banned in 1997 in the United States and Canada.
How long does it take for BSE to develop in a cow? Two to eight years. The mean is said to be four to five years.
Do cows with BSE produce calves that have BSE? If maternal transmission occurs, it apparently is rare.
What is the "30-month rule" in the United Kingdom? In the UK, cattle younger than 30 months are being used for meat, because BSE does not appear to develop in exposed animals until later than 30 months of age.
What steps has our government taken to reduce the chances of BSE becoming a problem in our cattle? Importation of ruminant livestock from the United Kingdom was banned in 1989. Other countries where BSE has been found have been added to the list since then. In October 1997, feeding of tissues from ruminant animals to cattle and other ruminants (the primary method of transmission) was banned in the United States and Canada.
My dogs and cats eat pet foods containing cattle and sheep protein byproducts. Are they at risk for BSE? There is no indication that BSE occurs in dogs – although BSE has been diagnosed in more than 100 British cats. The pet food industry in the United States has taken steps to protect itself against financial liability by adopting measures to keep ruminant byproduct protein from areas where BSE exists out of pet food products.
What about zoo animals? BSE-like disease was seen in ruminants in the United Kingdom, large cats in the United Kingdom and nonhuman primates in France. Feed containing rendered ruminant byproducts from diseased cattle is thought to have been the source in these cases.